In a prior patent application, U.S. Ser. No. 933,083, filed Nov. 20, 1986, Applicant described a method for aminating materials of this type to produce products having new and unusual properties, rendering same useful for a variety of purposes, including as fillers in plastic, rubber and other systems. These products can also be more generally regarded as intermediates for subsequent functionalization.
In a further patent application, U.S. Ser. No. 943,669, filed Dec. 17, 1986, Applicant disclosed a method for producing a layered lattice silicate which is surface modified with an organic material, by contacting the silicate (such as a kaolin) with an organic monomer, co-monomers, or a prepolymer, and effecting surface polymerization in situ in the presence of a gaseous hydrogen atmosphere.
It has now been found that aspects of these two processes can be combined to produce a yet further filler clay having unusual and highly desirable properties, e.g. as a filler for plastics.
The invention is applicable to layered silicates of the type which can be represented by the general formula E.sub.i M.sub.x Si.sub.y O.sub.n (OH).sub.m where M is Al, Mg, or Fe, x=2 to 6; y=2 to 8, n=2 to 20, m=0 to 8, and E.sub.i is one or more exchangeable ions (K, Na, Mg, Ca, Ba, Fe, Li, etc.).
In a 1979 article by the Soviet authors Savchits, Romanovskii, and Egiazrov, entitled "High Temperature Amination of the Surface of Oxide Catalysts", it is reported that the surface hydroxyl groups of high surface area aluminosilicate catalysts can be replaced by surface bound NH.sub.2 groups via a high temperature gas stage reaction with ammonia. This reference is concerned with examining those conditions under which ammonia does not modify the surface of the catalysts, and has no applicability to layered crystalline mineral materials such as the clay materials that are of primary interest to the present invention.
In accordance with the foregoing, it may be regarded as an object of the present invention, to provide new types of surface modified layered lattice silicate pigments, which are totally and directly compatible with the polymer systems to which they may be added as fillers, and which when so used provide outstanding improvements in the mechanical and other useful properties of the filled system.
It is also an object of the invention to provide a method of surface modification of layered lattice silicates in which improved bonding of modifier to the silicate surface is achieved.
It is a further object of the invention to provide a relatively simple, and effective process, for preparing the aforementioned surface modified pigments from layered lattice silicates, such as aluminosilicates, and which enables preparation of such products with a wide variety of compatibility characteristics for use in desired polymer matrices.
It is a yet further object of the present invention, to provide a process and products, which enable the production of filled systems, for example, resin-filled systems, incorporating the products of the invention, which have superior properties with respect to mechanical aspects of same, as compared to prior art filled systems based upon prior art kaolin clay, and similar fillers.